To add overall mass to the adominal area you will need some resistance just like any other muscle. When doing this only work the abs 2-3 times a week tops. If you have access to a full workout facility try bent over cable crunches or a machine crunch that you can add weight to. Follow this exercise up with hanging leg raises, do them slow and keep the form strict.
__________________ "I have found the Iron to be my greatest friend. It never freaks out on me, never runs. Friends may come and go. But two hundred pounds is always two hundred pounds."
-Henry Rollins |